SONOMA, Calif. — Clint Bowyer raced to his first victory on a road course, and first with Michael Waltrip Racing, by holding off Kurt Busch at Sonoma.

Bowyer dominated Sunday’s race by leading 70 of the 112 laps. Defending race winner Busch, in an unsponsored car, was all over the bumper of Bowyer’s Toyota late and got a final shot at taking the win away when caution flew with four laps remaining.

Only Busch damaged his car with roughly eight laps to go, and he worried the entire caution period whether his Chevrolet was ruined and had no chance of catching Bowyer through the two-lap overtime sprint to the finish.

Bowyer raced side-by-side with Busch at the green flag, then cleared Busch and pulled away for the win.

“Kurt raced me clean, he bumped me and roughed me up, but never did anything to jeopardize either one of us,” Bowyer said.

Bowyer, who left Richard Childress Racing at the end of last season to join MWR, had to walk to Victory Lane to celebrate with his new crew after his car ran out of gas.

“I’m super excited for everybody involved,” Bowyer said. “To switch teams like I did was a huge risk and a chance for me, and it was a chance to showcase my talents.”

It was a strong day all-around for MWR, which got a fourth-place finish from Brian Vickers, who was back to NASCAR after racing last weekend at Le Mans. Martin Truex Jr. led 15 laps, and was running in the top 10 until a late-race incident dropped him to 22nd.

“Everybody is just working together,” Bowyer said. “That’s something we are very proud of.”

Tony Stewart passed Busch on the final lap to claim second, but said it was because Busch’s car was struggling.

“Every time he would go in the corner, the rear end would shift, and it was running him to the outside of the track on entry and it was screwing his corner up,” Stewart said. “Kind of got it by default there to a certain degree. Once we got by there, we just were not close enough in that last lap to get to Clint.”

Busch finished third. He was emotional after — Busch missed Pocono earlier this month because he was suspended by NASCAR for verbally abusing a media member — and said he was thrilled to compete for the win in an underfunded, unsponsored Phoenix Racing car.

“It’s an amazing day, when you can do what we did,” Busch said. “I’m a little choked up because A: We were in position. B: I was very considerate to Bowyer, who was going for his first win with the new team. And then C: which is most important, I made a mistake, I got into those tires in turn 11.”

Busch, who has struggled with his temper on and off the track, saw a silver lining in his strong finish.

“If I can get my head on straight here, and after the race, then I could be able to race every weekend and go for victories,” Busch said.

Vickers was fourth for MWR, followed by Hendrick Motorsports teammates Jimmie Johnson and Jeff Gordon.

Most thought the race would be a runaway win for either Ambrose or Gordon. It wasn’t.

Ambrose led the first 11 laps before plummeting through the field, and said the setup on his car was off.

“We really missed it,” he said. “We missed it bad, and we did good to recover and get a top-10 out of it. We will take it and move on. We got the pole and had a lot of speed; we just missed it for the race.’’